This invention relates to photoelectric switches used to detect the presence or absence of an object. More particularly the invention relates to diffuse reflective type photoelectric switches wherein the light source and the detector are on the same side of the object. Specifically the invention relates to switches of the aforementioned type which are suited for use in an industrial environment of atmospheric contamination.
It is desirable that such switches be adjustable to provide a strong light signal to maintain good operational reliability under environmental contamination, but to preclude nuisance signals from background surfaces caused by the strong light signal. A preferred method of adjustment is to vary the angle of convergence between the source beam and the detector beam wherein the two beams intersect at the surface of the object to be detected. Such adjustment should be simple, readily accessible yet protected from unintentional adjustment and from the environment, and should preferably include an indication of the adjustment.